90Runner

Will replacing my O2 sensor help with my fuel economy?

thook

Depends on if the sensor is the problem, if you have a problem. What kind of mileage are you getting?

90Runner

I haven't narrowed it down because of my gearing and tire size my speedo is off. But I'm noticing even with my mods my fuel economy is off from what I was getting using the trip meter.

thook

Well, if you can't really determine you're fuel mileage there's not much point in fixing things that may not be broken. I'd say if you aren't getting any CEL codes for the O2 sensor, then there's nothing wrong with it. Find out what mileage you're getting first. Then, determine if something else is wrong.

iamsuperbleeder

In my 91 PU 22re, I got no CEL for my O2 sensor, and it was shot. OHMed way outta spec cold or hot, so I replaced it and pretty much doubled my gas mileage. Test it first if you can though, cause their not cheap... I managed to find a killer deal on eBay for a brand new Bosch one...

thook

Interesting. But, that's not the first time I've heard this, either.

I feel the same way. Test it before replacing. Same goes for anything, in my book.

About the Bosch sensor....
I found the sensors I bought at O'Reilly didn't fit tight in the manifold port. That threaded portion that the flange screws on to was too big to allow the flange to seat against the manifold snug. I pulled it off and found the flange to be bent over from tightening it down. I even when back to O'Reilly to get a replacement and the other Bosch sensors they had were like that.

iamsuperbleeder

mine was a direct replacement, not the one that threaded into the bolt on adapter... Bosch # 15711

thook

Since I'm not totally familiar with your year model, is your O2 sensor on the manifold or down further on the exhaust? I looked in the '93 FSM. It's on the exhaust pipe just before the cat. On my '86, it's right on the manifold.

iamsuperbleeder

further down, just before the cat

thook

Oh, I guess that esplains it, then.

Well, if you had a pre '90's 22re I'd say don't get a bosch..lol. The ND model fits perfect, though.

Anyway, that's odd you didn't get a code. I can't get away with that on my '86. Anytime there's a fuel/oxygen imbalance, the ECU picks up on it right away. After over a year of the CEL O2 code coming on, I've finally....I mean FINALLY!....tracked it down to the AFM. It's sucks because it passed every test covered in the FSM. But, last Sat. I swapped AFM's with My99 (Kyle....who lives near me) and my truck ran better. Finally after running a test the FSM didn't cover, I discovered the ohm readings to fluctuate when the door was moved from closed to wide open. On his....which is brand new....it reflects smoothly. The resistance goes from low at closed to high about midway and low again as it reaches wide open. Mine had drop outs along the way.....just like a bad TPS does when testing the VTA linear restistance.

Zachary

I am having a similar problem. I just bought a 90 pickup with the 22re. and someone cut the o2 sensor wire off and I cant find it anywhere to replace the sensor. I have a new sensor but nothing to wire it into. Normally there is a little yellow plug attached to a grey wire but I cant find it anywhere. I'm also kind of thrown because the second o2 is before the catalyc converter. And from my experiance they are supposed to have one on the manifold and one downstream of the cat. HELP

thook

A '90 model won't have the sensor located at the manifold. That's only for earlier models with a single wire/non-heated sensor. Yours, a 4 wire heated unit, will be located down on the frame rail before the CAT.....which sounds like what you're trying to identify as the secondary O2. And, if your truck is designed for Fed. emissions and not CA, then you probably don't even have a post CAT sensor.